In the hours before and after journalist Jamal Khashoggi was killed inside the Saudi Consulate in Istanbul, Saudi Crown Prince Mohammed bin Salman and a senior aide who allegedly oversaw the assassination exchanged multiple messages, according to people familiar with the matter.

The communications between the two men are another piece of evidence tying the crown prince to the killing of Khashoggi, a former palace insider turned prominent critic, who also was a contributing columnist to The Washington Post.

The CIA included the existence of the messages in its classified assessment that Mohammed is likely to have ordered Khashoggi’s death, a view that agency officials have shared with members of Congress and the White House.

Mohammed exchanged the messages on Oct. 2 with Saud al-Qahtani, one of his closest aides and a fierce public supporter who has kept a blacklist of those he deems disloyal to the kingdom. The content of the messages, and what form the messages took, was not known, according to people familiar with the matter.

Citing portions of the CIA’s written assessment, the Wall Street Journal first reported on Saturday that Mohammed had sent at least 11 messages to Qahtani before and after the killing.

The CIA has rated its assessment that Mohammed was involved in the killing at “medium-to-high confidence,” and privately, officials have said it is inconceivable that the prince, who exercises total authority over the government, could not have known about such an audacious operation. The Post had previously described officials as saying that the CIA had high confidence in its assessment.

“The accepted position is that there is no way this happened without him being aware or involved,” said a U.S. official familiar with the CIA’s conclusions. The CIA has declined to comment, and people familiar with the intelligence said the agency has not found any single piece of evidence that irrefutably links Mohammed directly to the killing.

Trump administration officials on Sunday continued to stress that point and emphasized the importance of the United States maintaining a close relationship with Saudi Arabia. The kingdom has acknowledged that its operatives killed Khashoggi, but it says the operation was not authorized by the crown prince and was undertaken by rogue actors.

“I have read every piece of intelligence that is in the possession of the United States government,” Secretary of State Mike Pompeo said in an interview with CNN on Saturday, “and when it is done, when you complete that analysis, there’s no direct evidence linking him to the murder of Jamal Khashoggi.”

Pompeo, who declined to comment on the CIA’s classified assessment, said the United States was working closely with Saudi Arabia on major foreign policy issues, including Afghanistan, and that the kingdom was a vital regional counterweight to Iran.

“They are a relationship that has mattered for 70 years across Republican and Democrat administrations alike,” said Pompeo, who previously served as the CIA director. “It remains an important relationship, and we’re aiming to keep that relationship with the Kingdom of Saudi Arabia.”

Secretary of Defense Jim Mattis said the question of holding the killers responsible and the strategic importance of the U.S.-Saudi relationship were separate issues.

“Accountability for the murder of Khashoggi stands alone. It is distinct from any other factor going on,” Mattis said in remarks at the Reagan National Defense Forum in California.

“Right now, we do not have a smoking gun,” he said, noting that he had seen all the latest intelligence in the matter as of Friday. “We do not have a smoking gun [showing] that the crown prince was involved. We certainly need to continue to explore . . . all aspects of the murder and find anyone who was involved, but that should not in any way dissuade us from basically confronting Iran,” which the Trump administration views as its major adversary in the Middle East and one that Saudi Arabia is essential to confronting.

Responding to the CIA’s findings, a Saudi official said in a written statement that Mohammed “communicates regularly with various senior officials within the Royal Court on different matters. At no time did [he] correspond with any Saudi officials in any government entity on harming Jamal Khashoggi, a Saudi citizen. We continue to categorically reject any accusations based on speculations.”

Qahtani has emerged as a key player in the killing and a compelling link to the prince. He shows up in another portion of the CIA’s assessment: An alleged member of the Saudi hit team that U.S. and Turkish officials said Qahtani oversaw, Maher Mutreb, called Qahtani from inside the consulate to inform him Khashoggi was dead, The Post has previously reported. Mutreb, a security official who was often at the crown prince’s side, is seen on security camera footage entering and leaving the consulate on the day Khashoggi was killed.

The U.S. intelligence community also has intercepts of communications before Khashoggi was killed that show Mohammed had ordered an operation to lure him back to Saudi Arabia. Friends of Khashoggi’s have said that Qahtani called the journalist and raised the potential of his working for the crown prince if he would end his self-imposed exile in Virginia and return to his native country.

Communications that the United States intercepted in July show that Mohammed had asked senior Saudi intelligence officials about the status of a plan to lure Khashoggi back to Saudi Arabia, according to one intelligence official.

President Trump, who also has been briefed on the CIA’s findings, has been equivocal in assigning blame to the crown prince, who works closely with the president’s son-in-law and senior adviser Jared Kushner on Middle East issues.

“Maybe he did or maybe he didn’t!” Trump said in a statement last month, adding that the true culprits might never be known. The president has said that the strategic relationship with Saudi Arabia and the benefit to the U.S. economy from Saudi arms purchases are too important to rupture over the killing of Khashoggi, which he has condemned.

But the latest revelation of intelligence connecting Mohammed and his aide Qahtani to the killing may increase pressure on the administration to take more punitive steps.

The Treasury Department has sanctioned 17 individuals it said were involved in Khashoggi’s death, including Qahtani, Mutreb and the Saudi consul general in Turkey, Mohammad al-Otaibi. But some members of Congress have called for further action, and Republicans have begun defecting from the administration over its support for the Saudis.

Last week, in a rebuke of Saudi Arabia and the administration’s handling of the Khashoggi case, a majority of the Senate voted to advance a measure to end U.S. military support to Saudi Arabia for its war in Yemen against Iranian-backed militants.

Mekhennet reported from Frankfurt, Germany. Missy Ryan in Simi Valley, Calif., and John Hudson and Ellen Nakashima in Washington contributed to this report.